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Utilize bandwidth of two T-1's from one provider

I currently have two T-1's with one provider and one with another as I await a fiber install. My question is, is there a way to utilize the bandwidth of the two T-1's from one provider in such a way that one or two customers of mine can burst to the combined bandwidth of the two T-1's.

I don't want to go the IMA route, as this is only a temp situation. I also have a third T-1 with another provider. I am running BGP and believe I am load balancing across all three. I have a default route to all three. Won't this just route based on source IP address out different interfaces? What I'm wondering is if a customer is streaming out more than 1.5 megs to one address, how can I make sure the traffic will use both paths? Some of the config below, 7206vxr: Thanks, Mitchel

Here's some of the config, 7206vxr: 
ip as-path access-list 1 permit ^$ ip as-path access-list 1 deny .* ip as-path access-list 2 deny ^6347 3549$ ip as-path access-list 2 deny ^6347_[0-9]*_3549_[0-9]*$ ip as-path access-list 2 permit ^6347_[0-9]*$ ip as-path access-list 2 permit ^6347_[0-9]*_[0-9]*$ ip as-path access-list 3 permit ^3549$ ip as-path access-list 4 permit ^6347$ ip as-path access-list 111 permit ^3549.*2554.*$ !PSI group A=2554 Carrier 1=3549 ip as-path access-list 111 permit ^3549.*6347.*$ !Carrier2=6347 ip as-path access-list 112 permit ^6347.*$ !Carrier2=6347 ip route Serial1/0:0.1 ip route Serial1/1:0.1 ip route Serial2/0:0.1 I have this for 5 of the clas "C" blocks I own. access-list 150 permit ip x.x.x.0 any And this for the remaining 4. access-list 198 permit ip host x.x.x.0 host route-map Carrier 1 permit 10 match as-path 112 set local-preference 100 ! route-map Carrier 2 permit 10 match as-path 2 set local-preference 150 ! route-map Carrier 2 permit 20 ! route-map Carrier 2 permit 10 match as-path 111 set local-preference 80 ! route-map MAP1 permit 10 match ip address 199 set as-path prepend 13853 13853 ! route-map MAP1 permit 20 ! route-map MAP2 permit 10 match ip address 198 set as-path prepend 13853 13853 ! route-map MAP2 permit 20

Thanks for your help!
The way you can do this is by using Cisco's per packet based load balancing. You will need to use Cisco's "Cisco Express Forwarding (CEF)" feature set, so you'll need to check to make sure that you have a version of IOS that supports it, and enough memory, you may need to check it out on Cisco's Web site to be sure.

Assuming the above you can turn on per-packet based load balancing using this command:

ip load-sharing per-packet
Be wary, however. There is always a very good chance that when you do per-packet load balancing that you'll be unintentionally re-ordering the sequence of packets. This can cause serious TCP performance problems because the TCP stack on the far end will have to buffer and re-order the packets. Also keep in mind that this will only be effective for your outgoing traffic. You would need your service provider to also enable this feature to get the load balancing working this way for your inbound traffic. If this is a temporary situation, I would highly recommend leaving things the way they are until your fiber comes in, unless your users have a specific need for more than 1.5Mb/s of traffic at a time, overall performance will likely be better sticking with the way things are.
(Answered by Brandon Ross, VP of Operations, Sockeye Networks.)

This was last published in August 2002

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